The effect of an intrauterine viral infection on the skin follicles of sheep

Border disease of sheep is a transplacental viral infection of the foetus. In medium and fine fleeced breeds, the most consistent of the pathological changes is permanent primary follicle enlargement, first apparent at 115 days gestation and accompanied by increased fibre size and frequency of fibre medullation. A tendency for fewer secondary follicles to develop in Border disease is probably an indirect consequence of infection.